A typical SIP scenario involves one or more proxy/re-direct servers as shown in FIG. 1. The “trapezoidal” arrangement shown therein includes a caller (UA1) entity and a called (UA2) entity. The UA1 caller may be anyone of a variety of user equipments (UEs) such as a properly equipped laptop, PDA, wireless cell phone capable of transmitting and receiving data as well as voice, and so forth. One important SIP feature is the ability to invite new participants to a call.
A user is identified in SIP using an SIP uniform resource identifier (URI) which may, for example, be UA1 at Domain (A). The Domain (A) server, Proxy 1, determines an SIP server for Domain (B), in this case, Proxy 2, using directory name service (DNS) procedures. During the message exchange, the caller UA1 and called UA2 entities exchange addresses at which they would like to receive communicated media from each other.
Once session establishment is completed, the caller/called entities can exchange data directly without involvement of the SIP proxies, such as Proxy 1 and Proxy 2. Conventionally, the control signals are communicated as illustrated by control signal lines CS via the proxy servers while the media content is shared as illustrated by media line MS.
Conventional techniques require that users in a particular network must always use the SIP proxy servers of that network operator in order to establish a SIP session. Third party application providers make their servers available to the network operator via open interfaces. The network operator makes these third party servers, and the applications they provide, available to the user via proxy servers within their networks. Typically, the network operator charges the user for access to the service with only a small amount of the revenue passed through to the third party application server provider.
The servers in the operators network are used to provide access to the third party application servers. The network operator controls the use of these servers and as a result, also controls access to the third party application servers. The present invention enhances access to third party application servers from user devices attached to operator networks and also provides the ability to increase the revenue stream for those services to the third party providers.
The objective of the present invention is to address scenarios where SIP is employed for contacting a third party application or content server transparently. The motivation behind this invention is the provision of a transparent means of network traversal to access third party application and content servers located outside of the operators' network.